This invention relates to optoelectronic devices and more particularly to a light emitting device fabricated from a semiconductor material and to a method of generating light in a semiconductor material.
Avalanche electroluminescent light emission in single crystal indirect bandgap semiconductors (e.g. silicon) is generated by the interaction between mobile carriers (e.g. recombination of electrons and holes) and lattice phonons in a reverse biased pn junction. The internal quantum efficiency (number of photons generated per electron) can be enhanced if “cool” (low energy) carriers are injected into the reverse biased junction from a closely spaced forward biased junction to interact with the “hot” energetic carriers within the depletion region.
However, in conventional devices, the carriers injected from the forward biased junction will be injected across all of the forward biased junction area (sidewalls and bottom wall). This means that only a relatively small percentage of all the injected carriers reach the reverse biased depletion region, to initiate light generation. The carriers not reaching the reverse biased avalanching depletion are lost and represent device current not being utilized for light generation, thus reducing the power efficiency of the light source.